There is a significant body of literature on the association between maternal depression and child behavior but considerably less evidence on the effects of neighborhood social conditions on both of these outcomes. Although there are prevention programs at individual and family levels, the potential for neighborhood level interventions has received less attention. The research proposal below will inform future theory and research on neighborhood level research and prevention mechanisms. The proposed study will use longitudinal data from a large-scale population-based study across urban, rural and suburban areas of Los Angeles County grounded in theories of neighborhood level determinants of health, providing the opportunity to refine the theoretical tradition of collective efficacy and neighborhood disorder by testing these theories, as well as adding empirical evidence of 1) the existence and effect, if any, of neighborhood disorder on maternal depression across diverse neighborhoods in LA County, 2) whether neighborhood disorder affects childhood internalizing and externalizing behavior and 3) the reciprocal relationship of maternal depression and child behavior within the social context of the neighborhood.